Arc interrupter



June 8 1926.

E. THOMSON ARC INTERRUPTER Filed Feb. 27, 1924 Inventor- Elihu 'T'horn SOT-1, flw

His Attorneyelectrode or of the arc.

Patented June 8, 1926.

UNITED STATES 1,5ss,210 PATENT OFFICE.

ELIHU THOMSON, OF SWAMPSCOTT, MASSACHUSETTS, ASSIGNOR TO GENERAL ELEC TRIO COMPANY, A CORPORATION OF NEW YORK.

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Application filed February 27, 1924. Serial No. 695,589.

My invention relates to means for extinguishing an electric arc, and has for its object the provision of an improved arcextinguisher or interrupter which is of compact form and capable of enduring severe service.

It is well known that the flow of electricity in an arc is produced through a stream of metallic vapor or charged particles which passes from one electrode to the other under the influence of an electrostatic field existing between the electrodes. These particles bombard the electrodes, thereby tending to maintain the high temperature which facilitates their production and, in

order to interrupt the arc, it is necessary to produce a condition tending to reduce vaporizationat the electrodes. Any irregularity in the arc path interferes with the passage of charged particles between the electrodes because of the fact that, due to their momentum, these particles tend to move in straight lines. Such irregularity may be produced either by movement of the The arc may be moved by an air blast or a magnetic field so as .to bend or lengthen it and revent some of the particles from completlng the path between electrodes. The arc may also be displaced by interposing a non-conductor in its path. In accordance with my invention improved means are provided for utilizing a plurality of these agencies in quenching an arc.

My' invention will be better understood from'the following description when considered in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

Referring to the drawing, Fig. 1 shows an embodiment of my invention; and Figs. 2 and 3 show certain details of its construction.

'Fig. 1 shows a combined switch and arc extinguisher. The are extinguisher is preferably constructed throughout of insulating material and comprises members 1 and 2 which together with plates or slabs 3 and 4 form a passageway open at its two ends.

Extending through this passageway in a direction approximately parallel to the sides plates 5 is supported by the member 2. The plates 5 and 6 are shown as made in the form of a trapezoid, one edge of each plate 5 being embedded in the block 1, and one edge of each plate 6 being embedded in the block 2. The blocks 1 and 2 are held in spaced relationship by means of the sides 3 and 4 which may be attached to the blocks by means of olts extending into the holes 7. The inner or free edges of the plates 5 extend into the spaces between the plates 6 and the inner edges of the plates 6 extend into the spaces between the plates 5. It will be observed that the interleaving or overlapping of the two sets of plates 5 and 6 is not constant throughout the passageway but varies from one end to the other so that length of the path which must be followed in traversing the distance between the sides 3 and 4 varies through the length of the passageway.

The plates 5 and 6 are preferably made of an insulating material capable of enduring sudden changes in temperature such as fused quartz, for example. Among the other materials available for this purpose may be mentioned very low expansion glasses, materials known as lava in lava insulators, and highly compressed asbestos sheet-s filled with vitreous material or laid in mica to reduce their porosity.

The members 1' and 2 may be made of any suitable material possessing sufliciently high insulating properties suchas cement or concrete, for example.

In order to facilitate an explanation of the manner in which the arc extinguisher operates, I have illustrated it as combined with an electric switch comprising terminals 8 and 9, stationary contacts 10 andll and a movable bridging member 12 for interconnecting the contacts 10 and 11. The bridging member 12 is supported by an arm 13 fixed to the shaft 14. Supports 15 and 16, illustrated as fixed to the sides 3 and 4 respectively of the extinguisher. are provided with bearings 17 in which are supported the ends of the shaft 14. A lever 18 is provided for rotating the shaft 11 to move the bridging member 12 into engagement with the contacts 10 and 11. The lever 18 is biased to open position by a spring 19. A member 20 pivoted at point .21 and arranged to cooperate with a pin 22 is provided for locking the switch in its. closed position.

that it is bowed or bent and because it is forced to follow a zigzag path aroundthe inner edges of the plates. The length of this zigzag path of course increases as the arc is forced farther and fartherinto the passageway. An electromagnet may be used to force the auinto the passageway. In Fig. 1

this is indicated bypoles 23 and 24. Strips 25 and 26 conductively associated with the stationary contacts 10 and 11 are provided for facilitating the passage of the arc into the extinguisher. The manner in which a magnetic field acts to displace an arc will be reatlily understood without detailed explanation. While I have shown the magnet as arranged to produce a field in the same general direction as a straight line drawn between the terminals 10 and 11 it will be apparent that this arrangement is not essential to the operation of the extinguisher but that the magnet may be so arranged as to have its pole pieces adjacent the outer surfaces of the members 1 and 2. In this case the general direction of the magnetic field is perpendicular to instead of parallel to a line drawn between the terminals 10 and 11. In either case, withthe-proper connections of the magnet exciting wlndings the arc will be forced into the passageway of the extinguisher due to its tendency to surround the magnetic field. Other means such as an air blast, for example, may be utilized to produce the same effect. This is indicated in Fig. 1 by a pipe 27 shownin Fig. L; If expedient a magnetic field may be utilized in conjunction with an air blast, the air blast being controlled in response to movement of the switch and the exciting windings of the magnet being partially or wholly energized by the current of the arc. While the extinquisher has been shown as having its passageway extending in a horizontal direction, it will be clear that a vertical passageway may be provided and that the heat of the arc may be utilized to facilitate its movement into the passageway.

The number of plates and the length of the passageway will be determined largely by the operating voltage. In any case the arrangement should be such that the are is extinguished before it has traveled the entire length of the passageway and the insulation of the plates should be high enough to force the are around their inner edges as it pro-v gresses throu h the passageway and its length along t e sides of the sheets become greater and greater.

to cover all changes and modifications withv in the spirit and scope of my invention.

\Vhat I claim as new and desire to secure by Letters Patent of the United States, is

1. A device of the class described comprising means forming a passageway, and a plurality of longitudinal insulating plates spaced from one another laterally of said passageway and extending into the same from opposite sides thereof, the arrangement being such that the distance by which said oppositely extending plates overlap varies from one point to another along said passageway.

2. A device of the class described comprising means forming a passageway, a plurality of longitudinal insulating plates spaced from one another laterally of said passageway and extending into the same from opposite sides thereof, and means whereby an electric are established adjacent one end of and transversely to said plates may be forced into said passageway, the inner edges of said oppositely extending plates being arranged to increase the length of said are as it travels along said passageway.

3. A device of the class described comprising means forming a passageway, a plurality of longitudinal fused quartz plates spaced from one another laterally of said passageway and extending into the same from opposite sides thereof, and means whereby an electric are established adjacent one end of and transversely to said plates may be forced into said passageway, said oppositely ex tending plates being overlapped at their inner edges by a distance which increases from one end of said passageway to the other.

4. A device of the class described comprising means forming a passageway, a plurality of longitudinal insulating plates spaced from one another laterally of said passageway and extending into the same from opposite sides thereof, and means for producing a magnetic field whereby an electric are established adjacent one end of and transversely to said plates may be forced into said passageway,

the inner edges of said oppositely extending plates being arranged to increase the length of said arc as it travels along said passageway.

In witness whereof, I have hereunto set my hand this 23rd day of February, 1924.

ELIHU THOMSON. 

